Extending network coverage, reducing power consumption and increasing network capacity and efficiency are some of the technical challenges which affect the design and deployment of mobile communications networks. One approach to reduce the power consumed by a user device and to increase network efficiency is to decrease the time spent transmitting and receiving signals and recovering data from received signals at both user devices and serving base stations. For example, if it is known by a user device that data intended for it is not to be transmitted within a predetermined period of time, the user device is able to cease recovering data from signals received during this period of time, thus reducing power consumption. Likewise, network resources can also be freed-up because the serving base station will not transmit data to the user device during this period. This approach is known as discontinuous reception. During discontinuous reception, data intended for the user device is periodically transmitted by a serving base station and data is only periodically recovered from signals transmitted by the serving base station, thus allowing the user device to periodically power-down its receiver when it knows that no data will be transmitted to it.
In cellular mobile communications networks, base stations are deployed to provide radio coverage to communications terminals. However each base station will have a limited coverage area and so, as far as possible, the coverage area provided by each base station is arranged to overlap the coverage area of it's neighbouring base stations. In order to maintain an ability to communicate data whilst roaming throughout the coverage area of a mobile communications network, a communications terminal is arranged to “handover” or “hand-off” from one base station to another as the communications terminal passes out of the radio coverage area of one base station and enters the coverage area of another base station. If handover is not successful then link failure may occur between the communications terminal and the mobile communications network. Re-connecting to the mobile communications network after link failure is often a resource intensive procedure both in terms of communications terminal resources and network resources, and also disrupts communications between the communications terminal and the serving base station. It is therefore desirable to reduce the likelihood of link failure.